Toxic exudate from the hard coral Goniopora tenuidens.

Ten colonies of Goniopora tenuidens were placed individually in sea water for 1 hr after which time the sea water was assayed using toxicity to another hard coral Galaxea fascicularis and to other colonies of G. tenuidens. Sea water from eight of the 10 colonies assayed was toxic to at least one of the bioassay organisms. Thus, G. tenuidens can extrude biologically active substances that adversely affect potential competitors, both interspecific and conspecific.